The 2006 Census is the first Census to have the variable Core Activity Need for Assistance. The Core Activity Need for Assistance variable has been developed to measure the number of people with a profound or severe disability. As with the ABS Surveys of Disability, Ageing and Carers, the Census of Population and Housing defines the profound or severe disability population as: 'those people needing help or assistance in one or more of the three core activity areas of self-care, mobility and communication, because of a long-term health condition (lasting six months or more), a disability (lasting six months or more), or old age'. More Detailed Description

There are many aspects which can affect the quality of Census data; the following information should be considered when viewing data on Core Activity Need for Assistance (ASSNP).

This data is based on responses to four questions on the Census form. Data is captured automatically from mark sense box responses where the risk of processing error is low. Sample checks of the data are undertaken to ensure an acceptable level of quality. Responses to the four questions are then combined to produce the single variable Core Activity Need for Assistance (ASSNP).

The non-response rate for 2006 was 6.4%. Part of this non-response is attributable to the 4.1% of persons in dwellings which were occupied on Census Night but did not return a completed form. Persons are imputed into these dwellings together with some demographic characteristics. However the values for ASSNP remain not stated.

ASSNP in the Census and other ABS data sources about disability

The Census 'Core Activity Need for Assistance' (ASSNP) concept was developed to indicate the disability status of people in Australia according to geographic area, and for small groups within the broader population. Of all ABS collections of disability data, only the Survey of Disability, Ageing and Carers (SDAC) is considered to comprehensively measure disability populations, and to provide rates of disability prevalence at the national and state levels. The census concept of ASSNP is related to the 'disability status' information collected in the SDAC and describes the more severe end of the disability spectrum. The population being measured by ASSNP is conceptually comparable with the SDAC population of people with a profound or severe core activity limitation i.e. those who always or sometimes need assistance in one or more of the core activities of self-care, mobility or communication.

The table below describes the key differences between the three disability measures collected by the ABS, and suggests for which purpose each should ideally be used. The rates of persons stating a Core Activity Need for Assistance in the Census are lower than rates for the same concept from the SDAC. This is as expected based on testing before the census. A similar effect occurs when the short disability module is used (as is the case in the General Social Survey) instead of the longer SDAC question set.

Despite the conceptual consistency of the measures, abbreviating the set of questions used to collect data on disability, as required for the census, reduces the number of people who can be classified as having a disability or to a particular level of disability, depending on the concept being collected. With regard to the concept core activity need for assistance (or severe/profound disability), the SDAC asks detailed questions about a range of tasks within each of the activity areas, the module (as used in the GSS) collapses this into a detailed prompt card still with each task within the activity areas clearly identified, and the census further collapses this into three questions (one for each of the activity areas), and a 'reason question' to exclude those people who indicate a need for assistance for reasons other than underlying disability, long-term health conditions or old age. The more the concept of need for assistance is collapsed into a reduced question set, the smaller the resulting population becomes because there are fewer 'trigger points' for inclusion. Other factors having an influence on population levels would be the difference between collecting the information via a personal interview or via a census self-completed paper or e-form questionnaire where one household member generally completes the form on the behalf of others.

ABS DISABILITY MEASURES

Disability status categories*

POPULATIONCENSUS

SHORT SURVEY MODULE

SURVEY OF DISABILITY, AGEING & CARERS (SDAC)

Profound

Core activity need for assistance(broad measure)

Disability status(broad measure)

Disability status(full measure)

Severe

Moderate

Mild

Employment/education restriction only

Concept not directly comparable with SDAC

*Derived from information collected about health conditions resulting in a need for help with core activities, amount of help needed, and employment/education difficulties.

Purpose of measure

Analysis ofcharacteristics of populations of interest(small areas, small population groups)

Analysis of characteristics ofpopulations of interest(according to survey topic)

Prevalence of disability in Australia

Number of questions

4

12

75

Output categories

Whether has a core activity need for assistance

Whether has a disability/all disability status categories

Whether has a disability/all disability status categories

Geographic outputs

All ASGC areas

Australia, most states(excl. remote areas)

Australia, most states(excl. remote areas)

Age scope

All persons

All adults(depending on survey design)

All persons

Dwelling scope

All dwellings

Private dwellings only

All dwellings(excl. gaols)

Most recent collection date

2006

2006 General Social Survey

2003

ASSNP in for the Aboriginal and Torres Strait Islander population

For the 2006 Census, rates of persons stating a Core Activity Need for Assistance for the Indigenous population are lower than rates for the same concept and population from the short disability module (National Aboriginal and Torres Strait Islander Social Survey 2002). This is consistent with what would be expected given similar findings for the general population discussed above. However, the data are affected by high non-response levels on Interviewer Household Forms used in remote communities and there is anecdotal evidence that comprehension of the questions on these forms may have been an issue. The ABS plans to do further analysis of Core Activity Needs for Assistance to identify any data quality issues which may be affecting this, and other, population groups.

The ABS aims to produce high quality data from the Census. To achieve this, extensive effort is put into Census form design, collection procedures, and processing procedures.

There are four principal sources of error in Census data: respondent error, processing error, partial response and undercount. Quality management of the Census program aims to reduce error as much as possible, and to provide a measure of the remaining error to data users, to allow them to use the data in an informed way.

When completing their Census form, some people do not answer all the questions which apply to them. In these instances, a 'not stated' code is allocated during processing, with the exception of non-response to age, sex, marital status and place of usual residence. These variables are needed for population estimates, so they are imputed using other information on the Census form, as well as information from the previous Census.

The processing of information from Census forms is now mostly automated, using scanning, Intelligent Character Recognition and other automatic processes. Quality assurance procedures are used during Census processing to ensure processing errors are kept at an acceptable level. Sample checking is undertaken during coding operations, and corrections are made where necessary.

The Census form may be completed by one household member on behalf of others. Incorrect answers can be introduced to the Census form if the respondent does not understand the question or does not know the correct information about other household members. Many of these errors remain in the final data.

More detailed information on data quality is available in the 2006 Census Dictionary (cat. no. 2901.0), in the section titled Managing Census Quality.